The research aimed to study and analyze the main determinants of public spending in the Libyan economy, and then determine the extent of the impact of each of them on the expansion that occurred in the volume of public spending during the period (1995-2020). Quantitative standard analysis: Unit root tests and the ARDL test. The results of the estimation concluded that there is a balanced relationship between the size of public spending “GEXP” as a dependent variable, the size of the gross domestic product “GDP” and the size of the public debt “PD”, the size of the population “POP”, and the growth rate of revenues. General ''TR'' in the long term. The results of the estimation in the short term also indicated that the volume of public spending for the current year “GEXP” had an inverse relationship with each of the variable of the size of the public debt (PD) for the current year, the variable of population size (POP-1) for the past year, and the variable of the growth rate. In public revenues (TR-1) for the past year on the one hand, and the inverse effect with each of the variable of the size of the gross domestic product (GDP-1) for the past year, and the variable of the size of the public debt (PD -1) for the past year, and the variable of the growth rate in public revenues ( TR) for the current year on the other hand